debugobjects: Extend to assert that an object is initialized

Calling del_timer_sync() on an uninitialized timer leads to a
never ending loop in lock_timer_base() that spins checking for a
non-NULL timer base. Add an assertion to debugobjects to catch
usage of uninitialized objects so that we can initialize timers
in the del_timer_sync() path before it calls lock_timer_base().

[ sboyd@codeaurora.org: Clarify commit message ]

Signed-off-by: Christine Chan <cschan@codeaurora.org>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Cc: John Stultz <john.stultz@linaro.org>
Link: http://lkml.kernel.org/r/1320724108-20788-3-git-send-email-sboyd@codeaurora.org
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 50 insertions, 0 deletions

diff --git a/Documentation/DocBook/debugobjects.tmpl b/Documentation/DocBook/debugobjects.tmpl
index 08ff908aa7a2..24979f691e3e 100644
--- a/Documentation/DocBook/debugobjects.tmpl
+++ b/Documentation/DocBook/debugobjects.tmpl
@@ -96,6 +96,7 @@
         <listitem><para>debug_object_deactivate</para></listitem>
         <listitem><para>debug_object_destroy</para></listitem>
         <listitem><para>debug_object_free</para></listitem>
+        <listitem><para>debug_object_assert_init</para></listitem>
       </itemizedlist>
       Each of these functions takes the address of the real object and
       a pointer to the object type specific debug description
@@ -273,6 +274,26 @@
         debug checks.
       </para>
     </sect1>
+
+    <sect1 id="debug_object_assert_init">
+      <title>debug_object_assert_init</title>
+      <para>
+        This function is called to assert that an object has been
+        initialized.
+      </para>
+      <para>
+        When the real object is not tracked by debugobjects, it calls
+        fixup_assert_init of the object type description structure
+        provided by the caller, with the hardcoded object state
+        ODEBUG_NOT_AVAILABLE. The fixup function can correct the problem
+        by calling debug_object_init and other specific initializing
+        functions.
+      </para>
+      <para>
+        When the real object is already tracked by debugobjects it is
+        ignored.
+      </para>
+    </sect1>
   </chapter>
   <chapter id="fixupfunctions">
     <title>Fixup functions</title>
@@ -381,6 +402,35 @@
         statistics.
       </para>
     </sect1>
+    <sect1 id="fixup_assert_init">
+      <title>fixup_assert_init</title>
+      <para>
+        This function is called from the debug code whenever a problem
+        in debug_object_assert_init is detected.
+      </para>
+      <para>
+        Called from debug_object_assert_init() with a hardcoded state
+        ODEBUG_STATE_NOTAVAILABLE when the object is not found in the
+        debug bucket.
+      </para>
+      <para>
+        The function returns 1 when the fixup was successful,
+        otherwise 0. The return value is used to update the
+        statistics.
+      </para>
+      <para>
+        Note, this function should make sure debug_object_init() is
+        called before returning.
+      </para>
+      <para>
+        The handling of statically initialized objects is a special
+        case. The fixup function should check if this is a legitimate
+        case of a statically initialized object or not. In this case only
+        debug_object_init() should be called to make the object known to
+        the tracker. Then the function should return 0 because this is not
+        a real fixup.
+      </para>
+    </sect1>
   </chapter>
   <chapter id="bugs">
     <title>Known Bugs And Assumptions</title>